1. Field of the Invention
The present invention is related to detection of the phase of a signal and, more particularly, to a method and apparatus for detecting a phase angle from two information signals representing in digital form the Cartesian coordinates of the tip of a signal vector.
2. Description of the Related Art
There are numerous situations in which it is necessary to determine the phase of an oscillating signal. For example, determinations of the phase of signals derived from radar echoes are used in extracting the range rate of a target. Phase is also useful in determining the monopulse angle and to reduce the number of bits required for recording data.
Conventionally, radar signals are processed as digital signals after pulse compression representing the real and imaginary, or in-phase (I) and quadrature (Q) components of a received signal. Known techniques for determining the phase from these signals involve multiplication and division, including squaring some values and taking the square root of others. Thus, a device constructed to perform such calculations in real time requires extremely fast processors or specially constructed arithmetic processors for performing the calculations in hardware. As a result, most conventional radar systems do no utilize calculations of phase angle that are more precise than a determination of the octant of the phase.